containerhelper

#!/bin/bash

#This is free and unencumbered software released into the public domain.

#Because this script needs root to do some things, excessive amounts of
#checking have been done to terminate the script if anything fails.

#Read all instructions very carefully. When it asks to type "yes", it must be
#all uppercase or it will fail.

#Don't try to use absolute paths, it will probably break things.

#Make sure cryptsetup is installed
cryptCheck(){
    command -v cryptsetup > /dev/null
    return "${PIPESTATUS[0]}"
}

#check to see if loop is loaded
loopCheck(){
    grep -e "^loop" /proc/modules > /dev/null
    return "${PIPESTATUS[0]}"
}

#check to see if ext4 is loaded
ext4Check(){
    grep -e "^ext4" /proc/modules > /dev/null
    return "${PIPESTATUS[0]}"
}


#Create new container. 
createContainer(){

if [[ ! "$2" =~ ^-?[0-9]+$ ]]
    then
        echo "second number should be a number of bytes"
        echo "example: createContainer CONTAINER_NAME 128"
        return 1
fi

    cryptCheck
    if [[ ! $? == 0 ]]
        then
            echo "cryptsetup is not installed"
            return 1
    fi

    loopCheck
    if [[ ! $? == 0 ]]
        then
            echo "loop kernel module not loaded"
            echo "run: sudo modprobe loop"
            return 1
    fi

    ext4Check
    if [[ ! $? == 0 ]]
        then
            echo "ext4 kernel module not loaded"
            echo "try restarting the machine"
            return 1
    fi

    if [[ -f "$1" ]]
        then
            echo "The file ""$1"" already exists, pick a different filename"
            return 1
    fi

    echo "please wait... files over a few megabytes might take awhile"
    dd if=/dev/zero of="$PWD"/"$1" bs=1M count="$2"
    if [[ ! $? == 0 ]]
        then return 1
    fi

    LOOPDEV=$(losetup -f)

    sudo losetup "$LOOPDEV" "$PWD"/"$1"
    if [[ ! $? == 0 ]]
        then return 1
    fi

    sudo cryptsetup \
        --verbose \
        --verify-passphrase \
        --iter-time 4000 \
        luksFormat "$LOOPDEV"
    if [[ ! $? == 0 ]]
        then return 1
    fi

    MAPNAME=""$1"MAP"
    sudo cryptsetup luksOpen "$LOOPDEV" "$MAPNAME"

    sudo mkfs.ext4 "/dev/mapper/"$MAPNAME""
    if [[ ! $? == 0 ]]
        then return 1
    fi

    sudo cryptsetup luksClose "$MAPNAME"
    if [[ ! $? == 0 ]]
        then
            echo "failed to close "$MAPNAME""
            return 1
    fi

    sudo losetup --detach "$LOOPDEV"
    if [[ ! $? == 0 ]]
        then return 1
    fi


}

#mount container
mountContainer(){

    LOOPDEV=$(losetup -f)
    MAPNAME=""$1"MAP"

    sudo losetup "$LOOPDEV" "$1"
    if [[ ! $? == 0 ]]
        then return 1
    fi

    sudo cryptsetup luksOpen "$LOOPDEV" "$MAPNAME"
    if [[ ! $? == 0 ]]
        then return 1
    fi

    CRYPTDIR=""$HOME"/PRIVATEDIRECTORY/"$MAPNAME""

    mkdir -p "$CRYPTDIR"
    sudo mount --options uid=$UID /dev/mapper/"$MAPNAME" "$CRYPTDIR"

}

#unmount container
#The arguement used here should be the exact name of the container file that
#is mounted.
#example: unmountContainer CONTAINERFILE
unmountContainer(){

    MAPNAME=""$1"MAP"

    sudo umount ""$HOME"/PRIVATEDIRECTORY/"$MAPNAME""
    if [[ ! $? == 0 ]]
        then
            echo "failed to unmount "$1""
            return 1
    fi

    LOOPDEV=$(losetup -a | grep "$1" | cut -c -10)

    sudo cryptsetup luksClose "$MAPNAME"
    if [[ ! $? == 0 ]]
        then return 1
    fi

    sudo losetup -d "$LOOPDEV"
    if [[ ! $? == 0 ]]
        then return 1
    fi
}